In the processing of tubular knitted fabric, it is typical to provide for wet processing of the fabric, which is followed by drying. The processed fabric, emerging from the dryer, is typically at a relatively high temperature and is excessively dry. In some cases, it may be possible to leave some minimum degree of moisture in the fabric, by extremely careful control of the drying operation, but typically this is not very practical. In other cases, as where the wet processing operation prior to drying includes resin impregnation, the drying operation is utilized as a means for curing the resin in the fabric. This of course involves first driving off all of the moisture in the fabric, so that the temperature of the fabric may be raised to a sufficiently high level to effect curing of the resin, e.g., 325.degree.-350.degree. F. (163.degree.-177.degree. C.). Under these conditions, the fabric emerging from the dryer is both bone dry and extremely hot, and is not regarded as being in a desirable condition for gathering (e.g., by folding or rolling up) or for subsequent processing.
It has long been known to be desirable at this stage to remoisturize the fabric, substantially back to the moisture content that it will tend to regain naturally over a period of time. Also, in the case of fabric which has been dried at relatively high temperature for resin curing purposes, it is desirable to substantially reduce the temperature of the fabric before gathering. While the desirability of cooling and remoisturizing has long been known, accomplishing that objective with adequate uniformity and adequately high moisture regain, while at the same time avoiding condensation stains and the like, has proved to be elusive.
In accordance with the invention, tubular knitted fabric is wet processed in an extractor-pad or similar apparatus, which in itself may be of known design, and is then passed directly into a fabric dryer, which also may be of known design. Immediately adjacent the discharge end of the dryer there is provided a moisture conditioning station, through which the continuously moving web of tubular knitted fabric is directed. Importantly, the fabric web is arranged to enter a lower portion of the moisture conditioning chamber, and is guided veritcally upward therein during the conditioning process. If necessary, the fabric is directed vertically downward from the dryer discharge, in order to be able to enter the conditioning chamber at the proper level.
After moisture conditioning, the fabric is conveyed farther upward for a predetermined distance, providing at least a brief interval for thorough penetration of the moisture, after which the fabric may be engaged by guide rollers and guided to a gathering apparatus, which may be a folder or a roll up apparatus. The guide rollers are arranged whereby the apparatus-fabric surface contact conditions are relatively uniform on opposite sides of the fabric.
In accordance with certain specific aspects of the apparatus used to practice the method of the invention, the moisture conditioning chamber is provided with opposed sets of finely atomizing water spray nozzles, which are arranged in banks on each side, in closely spaced arrays, so as to be able to uniformly contact the full width of the fabric, on both sides, with finely atomized water spray mist. The fabric web advancing toward the sprays, is guided first in a generally horizontal direction, underneath a condensation guard. The fabric is then passed under a guide roller and directed vertically upward between banks of downwardly inclined spray nozzles. The condensation guard includes a forwardly projecting lip, which either lightly contacts or is in very close proximity to the plane of the upwardly moving fabric, to effectively prevent the migration of downwardly travelling condensation droplets toward and onto the horizontally moving, incoming fabric.
Tubular knitted fabric under any circumstances is an easily distortable material, and this is particularly true when moist. Accordingly, careful control is maintained over the tension in the fabric in the moisture conditioning zone.
In the process of the invention, a wetting agent is associated with the moisture conditioning step, in order to assure prompt and thorough penetration of the spray material and prevent its being held on the surface of the fabric. In some cases, this may be accomplished by introducing measured, small quantities of a wetting agent into the water supply leading to the spray nozzles. More advantageously, where the incoming fabric is resin treated in advance of drying, a rewetting agent may be incorporated in the resin solution, which enables ordinary water supplies to be utilized in the remoisturizing operation.
Pursuant to one of the more specific aspects of the apparatus used to practice the method of the invention, the moisture conditioning apparatus is constructed in a manner to simplify precise, individual control of each of a large plurality of spray nozzles, in order to assure virtual uniformity of moisture regain and conditioning across the full width of the fabric. To advantage, this is accomplished by providing a separately adjustable, visually observable flow rate gauge leading to each and every nozzle, such that the measured flow rate may be individually adjusted for each one. In addition, a master control valve is provided for adjusting the water flow to all the valves in common.
Important processing advantages are derived from the process of the invention, by reason of the advantageous moisture conditioning of the fabric. Among other things, it is possible for an all cotton tubular knitted resin treated fabric, being processed at a speed of about twenty-five yards per minute, to be given a moisture regain of as much as 5% or more during moisture conditioning. This amount of moisture regain can result in a significant increase in fabric width, in some cases as much as 11/2 inches, and easily as much as one-half inch. This significantly facilitates the subsequent finish calendering operations, in which the fabric is required to be spread to a finish width. Where stripe straightening is required to be performed in the finishing operation, this is simplified by the greater pliability of the conditioned fabric. Even in subsequent processing, where the fabric is being sewed into garments, the moisture conditioning has an advantageous effect. Because of the higher levels of moisture, so-called needle cutting of the fabric, which is sometimes experienced during high speed sewing, is reduced. On the subjective side, the conditioned fabric has a noticeably more pleasant feel, being both silkier and softer than an unconditioned fabric.
For a more complete understanding of the above and other features and advantages of the invention, reference should be made to the following detailed description of a preferred embodiment and to the accompanying drawings.